Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0085631 (agitation)
 12,064 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A novel, simple, and highly economical technique is described for a rapid gas chromatographic screening and quantitation of basic drugs in serum. The drugs are adsorbed directly form 1 ml of serum onto 400 mg of XAD-2 resin, encapsulated within a rigid, porous, spherical polypropylene capsule, 2 cm in diameter. The capsule also contains a ferromagnetic bar that provides controlled agitation of contents under the influence of a rotating magnet. Resolution and quantitation of samples spiked with 18 basic drugs are provided by a nitrogen detector. The yields are quantitatively linear in both sub-therapeutic and toxic ranges for most drugs; the extracts exhibit minimal background in the range of sensitivities indicated; total extraction time is 20 min.
 ...
PMID:Magnetically propelled, encapsulated XAD-2 and microphase extraction technique for a rapid quantitation of basic drugs in serum by GC. 714 58

An increase in the power input for agitation from 0.4 to 2.7 kw/m3 in oxytetracycline biosynthesis stimulated the antibiotic production due to an accelerated use of carbohydrate and nitrogen and an earlier transition of the culture to the phase of the antibiotic biosynthesis. The procedure for determination of the aeration and agitation conditions by the maximum rate of the oxygen uptake is described. The procedure is recommended for the use in the studies on determination of such conditions for the biosynthesis of of oxytetracycline in large apparatus.
 ...
PMID:[Effect of mass exchange conditions on the biosynthesis of oxytetracycline]. 714 81

By variation of nutritional and other external conditions we have determined the factors that limit the multiplication rate and the culture growth in Tetrahymena thermophila. The enriched synthetic medium of Kidder & Dewey (1951), a culture temperature of 29 degrees C, and aeration by agitation were chosen as reference conditions. The final cell density is increased by and proportional to the amount of the complete set of nutrients. Testing single nutritional factors or groups of them revealed that only nitrogen sources yield higher cell densities. But none of them or any combination is as capable of increasing the cell density as the complete medium. Therefore, the medium has to be considered as well balanced. Ammonia, cell density, O2 supply, and pH have been excluded as factors limiting the capacity for multiplication. There are no known factors promoting or inhibiting culture growth.
 ...
PMID:External factors limiting the multiplication potential of Tetrahymena. 732 73

A method has been developed, based on techniques used for isolating bacteria from the rumen, that enables human faeces to be fractionated into three major components. The method requires repeated, vigorous agitation of a suspension of faecal solids with detergent, the use of a stomacher, and high-speed centrifugation. By this means the faecal microflora are separated from faecal dietary-fibre residues. These two components, with water-soluble material in the stool, comprise 98.3 +/- 0.9% of faecal solids. The purity of the microbial fraction was demonstrated by Gram and plant stains and by scanning electron microscopy. Microscopic counts of the bacteria in each fraction of the stool showed that the microbial fraction contained 95% of the total bacteria. Chemical analysis of the component sugars indicated 6-7% possible contamination by non-bacterial polysaccharides. The bacterial pellet was 6% nitrogen, and accounted for 60% of the total faecal nitrogen. When faeces from nine healthy subjects on a metabolically controlled British-type diet were studied, bacteria comprised 54.7 +/- 1.7% of the total solids, fibre 16.7 +/- 0.8% and soluble material 24.0 +/- 1.3%. Bacteria therefore represent a much larger proportion of the faecal mass than was previously thought.
 ...
PMID:The microbial contribution to human faecal mass. 735 76

The operation of a cyclone bioreactor differs from conventional stirred tanks since the agitation is accomplished by means of a pumped recirculation loop. Oxygen transfer can occur across the swirling gas-liquid interface in the cyclone or from bubbles entrained in the recirculation loop. A cyclone bioreactor was scaled-up from a 1 dm3 bench top unit to a 75 dm3 Process Development Unit (PDU). A reduction in the aspect ratio was compensated for by extending the length of the recirculation loop and providing additional aeration. Performance of the two reactors for the production of microbial poly-beta-hydroxybutyrate (PHB) was compared under various operating conditions. The culture used for PHB production was Alcaligenes eutrophus DSM 545, grown on a mineral salts medium limited by the supply of nitrogen. The levels of dissolved oxygen obtained in the PDU were strongly dependent on the location at which the air was introduced into the reactor. However, with aeration balanced between two injection points and a similar level of power input, 17 J s-1 dm-3, the PDU was able to provide at least as much oxygen transfer capability as the laboratory-scale reactor. Under all conditions tested, the PHB accumulation by A. eutrophus was in excess of 80% of the biomass dry weight, although the yield on glucose was lower in the PDU than in the laboratory-scale reactor.
 ...
PMID:Scale-up of a cyclone bioreactor. 776 98

In microbroth cultures with RPMI 1640 medium, the growth yield of seven Cryptococcus neoformans isolates was unaffected by augmentation of the normal (0.2%) glucose concentration in the medium to 2%, and the addition of other potential carbon, nitrogen, and vitamin sources to the medium also failed to produce large changes in growth yield. However, macrobroth cultures of C. neoformans in RPMI 1640 that were agitated by rotation in air gave turbidities 6 to 37 times greater than those in identical cultures incubated statically, and similar levels of increase were seen whether the medium contained 0.2 or 2% glucose. Incubation of microplates under an oxygen atmosphere or with agitation by rotation led to an increase of up to twofold in growth turbidity of the yeast. The maximum increase was achieved by incubation with rotation and was dependent on the brand of microplate used. The findings implicate oxygen as a growth-limiting nutrient for C. neoformans. Incubation of microbroth cultures under conditions that enhance oxygen availability for antifungal susceptibility testing purposes may increase the speed of such tests and enhance the determination of MIC endpoints.
 ...
PMID:Oxygen as limiting nutrient for growth of Cryptococcus neoformans. 779 Apr 75

We describe the design and use of a device that enables the semiautomatic feeding of various quantities of liquid, milk-replacer diet. The apparatus consists of a programmable fraction collector (with attachments for preparative work) driven by a high-flow peristaltic pump. To reduce bacterial growth and lipid oxidation of the liquid diet, we kept the milk-replacer in an ice bath and bubbled a slow stream of nitrogen through it at all times. The liquid diet was kept in suspension by continuous recirculation and agitation. The device can be used to dispense prespecified amounts of either the same volume of feed, or a different volume to each of two groups of animals at regular intervals over 24 h; alternatively, by using the time-windows feature of the fraction collector, up to 11 different volumes can be dispensed to 11 animals. We present results of a preliminary trial in which we used the equipment to feed 11 pigs, weaned at 1 d of age, for 11 d. Daily maintenance and programming of two systems, including diet preparation and pig weight measurements, were accomplished in approximately 90 min. The feeder is simple to program and enables the feed intake of the pigs to be adjusted accurately for individual BW on a daily basis. The pigs had no diarrhea and grew well on the rations allocated to them.
 ...
PMID:A semiautomatic device for feeding liquid milk-replacer diets to infant pigs. 845 55

A fermentation process in Escherichia coli for production of supercoiled plasmid DNA for use as a DNA vaccine was developed using an automated feed-back control nutrient feeding strategy based on dissolved oxygen (DO) and pH. The process was further automated through a computer-aided data processing system to regulate the cell growth rate by controlling interactively both the nutrient feed rate and agitation speed based on DO. The process increased the total yield of the plasmid DNA by approximately 10-fold as compared to a manual fed-batch culture. The final cell yield from the automated process reached 60 g L-1 of dry cell weight (OD600 = 120) within 24 h. A plasmid DNA yield of 100 mg L-1 (1.7 mg g-1 cell weight) was achieved by using an alkaline cell lysis method. Plasmid yield was confirmed using High Performance Liquid Chromatography (HPLC) analysis. Because cells had been grown under carbon-limiting conditions in the automated process, acetic acid production was minimal (below 0.01 g L-1) throughout the fed-batch stage. In contrast, in the manual process, an acid accumulation rate as high as 0.36 g L-1 was observed, presumably due to the high nutrient feed rates used to maintain a maximum growth rate. The manual fed-batch process produced a low cell density averaging 10-12 g L-1 (OD600 = 25-30) and plasmid yields of 5-8 mg L-1 (approximately 0.7 mg g-1 cells). The improved plasmid DNA yields in the DO- and pH-based feed-back controlled process were assumed to be a result of a combination of increased cell density, reduced growth rate (mu) from 0.69 h-1 to 0.13 h-1 and the carbon/nitrogen limitation in the fed-batch stage. The DO- and pH-based feed-back control, fed-batch process has proven itself to be advantageous in regulating cell growth rate to achieve both high cell density and plasmid yield without having to use pure oxygen. The process was reproducible in triplicate fermentations at both 7-L and 80-L scales.
 ...
PMID:Automated fed-batch fermentation with feed-back controls based on dissolved oxygen (DO) and pH for production of DNA vaccines. 907 87

Mutant of Rhodotorula glutinis MTCC 1151 was found to produce high level of lipid (63.6% of biomass) as compared to parent strain (56.7% biomass). The lipid synthesizing capacity of mutant of R. glutinis was evaluated with different glucose concentrations, nitrogen sources, incubation time, and aeration-agitation. Maximum lipid yield (63.6% of biomass) was found with 5% glucose using ammonium sulfate (0.2%) as a nitrogen source under shake-flask conditions (50 ml broth in 250 ml conical flask at 125 rpm) after 4 days of incubation at 28 degrees C. The ability of ammonium sulfate to replace comparatively very costly yeast extract is highly appreciable.
 ...
PMID:Influence of cultural conditions on lipid production by mutant strain of Rhodotorula glutinis MTCC 1151. 931 36

This paper is the fourth in a series aimed at improving the understanding and operation of conventional agitated fermenters for the production of the commercially important gum, Xanthan. In the first, reproducible fermentations were established and this protocol was used in studies of different agitator types and of bulk mixing and dissolved oxygen concentration in the next two. Here, building on the previous work, the influence of different glucose feeding strategies on Xanthan production in a 20-L agitated fermenter under equivalent conditions of agitation and dissolved oxygen is reported. The biological performances in three types of fed-batch cultures (a two-step glucose addition, multiple glucose-pulse feeding and continuous feeding of glucose) are compared to two batch fermentations with different initial glucose concentrations. The work confirmed that improved performance cannot be achieved by increasing the initial glucose concentration above 50 g/L nor by a single 10 g/L pulse addition (initial glucose concentration of 40 g/L) while significant nitrogen is still present. On the other hand, the simple pulse and continuous feeding strategies, after nitrogen has been essentially exhausted and under conditions of nonlimiting dissolved oxygen and similar bulk mixing, can result in a greatly enhanced performance compared to batch fermentations. Using the final Xanthan gum concentration, the yield on glucose and the overall productivity as performance indices, values of 62 g/L, 0.82 g of Xanthan/g of glucose, and 0.72 g/(L.h), respectively, were obtained compared to literature values for conventional stirred bioreactors of 15-30 g/L, 0.27-0.86 g of Xanthan/g of glucose, and 0. 12-0.43 g/(L.h).
 ...
PMID:Enhancing xanthan fermentations by different modes of glucose feeding 954 78


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>